/*
 * [New BSD License]
 * Copyright (c) 2011-2012, Brackit Project Team <info@brackit.org>  
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 *     * Neither the name of the Brackit Project Team nor the
 *       names of its contributors may be used to endorse or promote products
 *       derived from this software without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package org.brackit.xquery.expr;

import org.brackit.xquery.ErrorCode;
import org.brackit.xquery.QueryContext;
import org.brackit.xquery.QueryException;
import org.brackit.xquery.Tuple;
import org.brackit.xquery.atomic.Bool;
import org.brackit.xquery.sequence.TypedSequence;
import org.brackit.xquery.xdm.Expr;
import org.brackit.xquery.xdm.Item;
import org.brackit.xquery.xdm.Iter;
import org.brackit.xquery.xdm.Sequence;
import org.brackit.xquery.xdm.type.SequenceType;

/**
 * 
 * @author Sebastian Baechle
 * 
 */
public class InstanceOf implements Expr {
	private final Expr expr;

	private final SequenceType expected;

	public InstanceOf(Expr expr, SequenceType expected) {
		this.expr = expr;
		this.expected = expected;
	}

	@Override
	public Sequence evaluate(QueryContext ctx, Tuple tuple)
			throws QueryException {
		return evaluateToItem(ctx, tuple);
	}

	@Override
	public Item evaluateToItem(QueryContext ctx, Tuple tuple)
			throws QueryException {
		try {
			Sequence sequence = expr.evaluate(ctx, tuple);

			if (sequence instanceof Item) {
				TypedSequence.toTypedItem(ctx, expected, (Item) sequence);
			} else {
				Sequence typed = TypedSequence.toTypedSequence(ctx, expected,
						sequence);
				
				if (typed != null) {
					Iter it = typed.iterate();
					try {
						while (it.next() != null)
							;
					} finally {
						it.close();
					}
				}
			}
			return Bool.TRUE;
		} catch (QueryException e) {
			if (e.getCode() == ErrorCode.ERR_TYPE_INAPPROPRIATE_TYPE) {
				return Bool.FALSE;
			}
			throw e;
		}
	}

	@Override
	public boolean isUpdating() {
		return false;
	}

	@Override
	public boolean isVacuous() {
		return false;
	}
}
